The former child actor Gary Coleman, who soared to fame as the precocious star of the US TV sitcom Diff'rent Strokes, has died at 42 after suffering a brain haemorrhage in a fall.

Coleman, whose character Arnold Jackson was the star of the show with his catchphrase "Whatchou talking about Willis?" – a regular jibe at his brother in the series which began in 1978 and lasted eight years.

Coleman was said to be "lucid and conscious" when taken to the Utah valley regional medical centre on Wednesday but later slipped into a coma, hospital staff said. His wife Shannon Price, 24, was with him when the decision was taken yesterday to turn off his life support machine.

Coleman had suffered from health problems throughout his life and this was the third time this year that he had been hospitalised.

A congenital disorder stunted his height to 4ft 8ins and by the age of he had already undergone two kidney transplants. Last year he underwent heart surgery.

Coleman, seemed blessed with comic timing when he first appeared in Diff'rent Strokes aged 10. His role as one of two African-American siblings adopted by a wealthy white man made him a global star by the time he was 11 but his popularity faded when the show ended.

According to People Magazine, Coleman amassed and lost $18m during his career. He lost most of his money in a protracted legal battle with his adoptive parents who had control of his wealth until he was 18. By the end, he was left with just $200,000. After his acting career ground to a halt he took a succession of menial jobs, including working as a security guard. Eventually he was forced to sell off his personal items and, in 1999, filed for bankruptcy.

However, he had recently returned to the small screen, moving to Utah in 2005 to appear in the show Church Ball, a comedy based around the world of Mormon basketball leagues.

Like many child stars, Coleman's adult life was dogged by personal problems. In 1998, he was convicted of punching a female fan who asked for his autograph. He was given a suspended sentence after he told the court that he thought the woman was about to attack him. "I was getting scared, and she was getting ugly," he said.

His three-year marriage to Price was tempestuous. The couple met on a movie set in 2005 and married two years later. Both Coleman and Price were arrested on separate occasions over domestic violence allegations.

In 2003 Coleman stood for governor in the California recall election, where he was placed eighth out of 135 candidates, with 14,242 votes.

He was also parodied in the award-winning Broadway musical Avenue Q, where a character named Gary Coleman is presented as the caretaker of a block of flats and sings the song "It sucks to be me". Coleman threatened to sue the show's producers but the lawsuit never materialised.

Last night, the actor's family issued a statement acknowledging the difficulties he had suffered in recent years.

He had "difficulties not only with health issues, but also with his personal and public life," they said in a statement. "At times it may not have been apparent, but he always had fond memories of being an entertainer and appreciates his fans for all their support over the years."